The present invention relates to printing devices used by computer systems and more specifically to printing devices that are configured to position the print heads for the expected printed output.
There are many types of printing devices for computer systems including laser printers, pen plotters, scanning head printers, impact printers and ink jet printers. Laser printers create an image by placing a charge onto a drum that attracts colorant particles, or toner, and transferring the colorant particles onto a sheet of paper. The sheet of paper is then passed through a fuser where the colorant is fused or melted onto the paper.
A pen plotter draws lines on a medium by moving a pen relative to a sheet of paper. By moving the pen in a scanning direction and moving the medium in a perpendicular direction, a two-dimensional image is created. A pen plotter may be used to create line drawings of any type, or area fills, by drawing lines right next to one another. In pen plotters, color images may be created by the use of different color pens. Typically, two to eight different color pens are used.
In a scanning head system both the print head and the paper (or, more generally, the print medium) are moved independent of each other. In this system, the print head is scanned across the medium and then the medium is advanced. Once the medium has been advanced, the print head is scanned for a next pass. A variation on a scanning head printer is to hold the printing device (such as a pen in an ink jet printer) stationary and pass the medium under the print head. These devices are referred to as fixed pin or fixed print head printing devices.
Impact printers use an ink bearing component, such as a ribbon, which is struck by a print head to write onto a printing surface. Typically, the print head moves along the width of the print medium and the print medium is transported longitudinally.
In an ink jet printer a jet of ink is projected out of a print head onto the surface of the object, such as paper, to be printed. The print head is moved along the surface of the print medium.
A printer utilizing a fixed print head keeps, as the name implies, the print head stationary and passes the paper or print medium under the print head to form an image. Movement of the print media may vary from system to system; in some systems the medium is moved back and forth several times to create additional details in the image. See, for example, U.S. Pat. Nos. 6,113,232 and 6,155,680, both of which are incorporated herein by reference in their entirety, which describe stationary pen ink jet printers.
In fixed pen printing systems, those in which printing is accomplished with a single pass of the medium under the pen or print head, the size of the printed image is limited by the size of the printing device, for instance the size of a nozzle array. The size of the printed image may be increased by using multiple print heads or pens positioned in sequence, effectively employing a larger print head. Such systems are described in, for example, U.S. Pat. Nos. 4,977,410; 5,589,868; 5,943,083; 6,290,316; and 5,966,149, all of which are incorporated herein by reference in their entirety, describing use of a plurality of print heads or a segmented or divided line head to print a full line across a page. Each of these methods increase the cost, complexity, and size of the printing device. Typically in each of these printing devices, the printable portion of the paper is determined by the location of the print head or pen with respect to the medium. In order to allow printing over the entire paper, numerous print heads, or one extended print head, can be constructed along one edge of the paper. With this configuration, a single color can be printed along an entire page in a single pass of either the print heads or the paper.
With today""s printing devices, printing on specialty media such as envelopes, labels or similar medium, requires either a versatile-multifunction printing device configured for the specific task, or requires a machine designed and dedicated specifically for that purpose. For example, a multi-purpose printer could be configured to print envelopes, or a printer can be purchased for printing envelopes.
One embodiment is directed to a printing system comprising a plurality of print heads for printing an image on a print receiving medium, print head actuators operable for individually repositioning the print heads to optimal locations for each print job, and software operable while a current print job is active for determining the optimal print head locations for a next anticipated print job.
Another embodiment is directed to a method for printing an image onto a print receiving medium comprising determining, while a current image is being printed, a desired subsequent printing position for one or more print heads, and repositioning, at the completion of the printing of the current image, one or more print heads to the desired subsequent printing position.
Another embodiment is directed to an apparatus for printing an image onto a print receiving medium comprising a plurality of print heads, means for repositioning each of said print heads from previous printing locations to desired print head locations in accordance with a determined desired print head location for each said print head on a print job by print job basis, means for determining said desired print head location for a next anticipated print job while a current print job is in process, and means for enabling said repositioning means immediately upon the conclusion of said current print job.